Grimlock is a tragic figure.  He was originally developed by the Decepticons as a soldier whose sentience would be based on artificial intelligence rather than an Ember.  However, his violent subroutines overrode his logic programming causing him to destroy the facility that created him.  Megatron was able to deactivate him and he was stored away, never to be used again.  However, when Optimus Prime learned of this creation, he stole Grimlock and reactivated him.  Offered a chance to revel in his violent tendencies, Grimlock eagerly joined Optimus Prime and serves as his most potent warrior.  Grimlock will not stop tearing through the enemy ranks until they are all destroyed or he can no longer move.  He simply cannot feel mercy and has little self control.  "I wish I had a thousand more like him!" says Autobot leader Optimus Prime.  Fortunately for the Decepticons, he doesn't.

Bibliography of significant appearances: All characters of the Botcon 2008, "Shattered Universe" are personas existing in an alternate reality.  Their story was featured in the 2008 convention comic, several of the Transformers Collector Club comics and a few prose-only stories including "Dungeons & Dinobots." 

Other appearances: